In U.S. Pat. No. 3,819,468, granted on June 29, 1974, there is disclosed a novel form of construction for a high temperature insulation module wherein the outer surface of the module consists of a mat of resilient ceramic fibers formed by combining in side-by-side relation thin strips cut from standard blankets of ceramic fiber insulation such that the fibers are oriented generally in planes substantially perpendicular to the hot face of the insulation module. The module was especially adapted to be fastened to the interior surfaces of a high temperature chamber, such as a furnace, by means of a unique method of stud welding, also disclosed in the above-mentioned application and more fully described in U.S. Pat. No. 3,706,870, issued Dec. 19, 1972.
This novel module construction eliminated to a large extent the tendency for the insulation material to crack and thereby lose effectiveness as a result of exposure to the continued cycles of heat-up and cool-down experienced in high temperature furnaces. Furthermore, the unique aspect of the insulation module construction, that is, with the ceramic fibers disposed generally perpendicular to the surface of the furnace wall, essentially eliminated a second problem previously encountered with the use of ceramic fiber insulation, that of devitrification and delamination of the outer surfaces of the insulation material. Finally, the ceramic fiber layer of the insulation module disclosed in that earlier application had the property of being resilient and significantly less inclined toward loss of structural integrity.
In the module disclosed in the above first-mentioned patent, the ceramic fiber mat was adapted to overlie an intermediate rigid insulating member positioned between the mat and the interior wall or surface of the high temperature chamber to which the module was to be attached. The primary function of this rigid base member was to give structural strength and rigidity to the final insulation module.
Because of the necessity of providing this rigid base member as part of the insulation module, additional manufacturing operations were involved. This obviously resulted in a higher cost for the module. Further, there were some limitations placed on the shape and size of the modules which would be available without special order. This was due to the fact that the hole for insertion of the stud on which the module would be mounted against the furnace wall was required to be cut through the rigid base member during the manufacturing operation.
Development has been directed toward manufacturing these modules at lower cost. While more efficient methods and apparatus for constructing such modules have been developed, there remains, nevertheless, a strong need for an effective insulation module which can be manufactured and installed at lower cost.